JPS6333825A - Plasma chemical vapor growth apparatus - Google Patents

Abstract

PURPOSE:To form a film having excellent denseness and flatness with a low bias voltage at a high depositing speed by providing an electric field forming mechanism for forming an electric field toward a sample perpendicularly and a mechanism for applying a magnetic field crossing the electric field to obtain a high density plasma. CONSTITUTION:A sample base 15 for mounting a sample 19, an opposed electrode 17 and a magnetic field applying mechanism 16 are provided. The electrode 17 is grounded, a bias voltage is applied to the base 15 by a power supplying mechanism 12 having a high frequency power source and an impedance matching circuit through a capacitor 13 to form an electric field directed perpendicularly to the sample 19. A magnetic field 18 crossing the electric field is applied in parallel with the base 15 by the mechanism 16 having an N-pole and an S-pole. Thus, electrons are repeatedly collided with material gas introduced perpendicularly to the magnetic field while moving in a cyclotron motion to accelerate the ionization. Thus, a high density plasma is obtained even in a high vacuum degree, and a film having excellent denseness and flatness can be formed with a low bias voltage at a high depositing speed.

Description

[Detailed description of the invention] [Industrial application field] The present invention relates to a plasma chemical vapor deposition apparatus.

[Conventional technology]

In manufacturing highly integrated semiconductor devices, a plasma chemical vapor deposition technique is required to form a film having excellent density evenly on a stepped portion.

Conventionally, the technology for this crosspiece was [s i dewa l
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Pour Depositionj Journal
Electrochemical 5ociety 19
There is a bias plasma chemical vapor deposition technique in which a film is formed by applying a bias voltage to a sample, as described in B5, pp. 2721-2725.

This bias plasma chemical vapor deposition apparatus basically consists of a vacuum evacuation system 3 for evacuating a reaction chamber 31, as shown in FIG. 3-a.
2, a reactive gas supply system 38, a grounded counter electrode 37, a power supply mechanism (high frequency power supply and impedance matching circuit) 33 for generating discharge plasma, and a sample stage 36;
It is composed of a capacitor 34.

In this device, since the sample stage 36 is connected to the power supply mechanism 33 via the condenser 34, the sample 35
A film is formed thereon with a bias voltage applied.

[Problems that the invention attempts to address]

In the conventional plasma chemical vapor deposition apparatus described above,
Since the pressure during film formation to obtain the plasma density necessary for film formation is as high as 10-1 to 1 O-2 Torr, the mean free path of ions is as short as 0.05 to 0.5 cm. As a result, fewer ions are accelerated perpendicularly to the sample surface by the bias voltage and collide perpendicularly to the sample surface. Therefore,
As shown in FIG. 3-b, using this conventional apparatus, a silicon oxide film 301 is formed on an aluminum wiring 302 formed on a silicon oxide film 303 formed by thermal chemical vapor deposition. However, there was a problem in that the flatness of the step covering was insufficient. Furthermore, when using conventional equipment, the bias voltage applied to the sample is as high as 100 OV or more, so if interlayer films of semiconductor integrated circuit devices are formed using conventional equipment, the underlying transistors may be damaged due to ion bombardment on the sample surface. There was a problem that the characteristics of the Furthermore, there is another problem in that the sample stage is sputter-etched by ions accelerated by this high bias voltage, and the materials constituting the entire sample stage are mixed into the formed film as impurities, deteriorating the film properties.

[Means for solving problems]

The plasma chemical vapor deposition apparatus of the present invention is a plasma chemical vapor deposition apparatus that deposits a thin film by decomposing a material gas by plasma discharge. It has a mechanism that applies all of the intersecting magnetic fields.

According to the present invention, an electric field is applied perpendicularly to the sample, and a magnetic field is also applied to cross this electric field, so that the electrons move in a cyclotron in the direction perpendicular to the electric and magnetic fields and repeatedly interact with the sampled material gas. Collisions and promotes dissociation, 1
Even in a high vacuum of 0-” Torr, the plasma density is 102 to 20% compared to that obtained with conventional equipment.
Produces a high-density plasma that is 103 times higher.

Therefore, even if pI4 is formed by lowering the bias voltage applied to the sample compared to the bias voltage applied to the sample in a conventional plasma chemical vapor deposition apparatus, the number of ions irradiated onto the sample surface is large. It has the advantage that a film with excellent density and flatness can be formed at a high deposition rate with a low bias voltage. Furthermore, since the film is formed at a low bias voltage, there is no damage to the sample, and sputter etching of the electrode is suppressed, resulting in a high-quality film with no impurities incorporated into the formed film. have

〔Example〕

Next, embodiments will be described with reference to the drawings.

FIG. 1-a is a longitudinal sectional view of the first embodiment of the present invention.

A sample stage 15 on which a sample 19 is placed, a counter electrode 17, and a magnetic field application mechanism 16 are provided in a reaction chamber 11 equipped with a gas supply system 20 and a vacuum exhaust system 14. The counter electrode 17 is grounded, and the sample stage 15 is connected to a power supply mechanism 12 consisting of a high frequency power source and an impedance matching circuit.
A bias voltage is applied via 3 to create an electric field directed perpendicular to the sample 19. A magnetic field 18 intersecting this electric field
is applied in parallel to the sample stage 15 by a magnetic field applying mechanism 16 consisting of a north pole and a south pole.

Next, a method of forming a silicon oxide film used on this device will be explained. A mixed gas of 5iH4 (monosilane) gas, Nz0 (nitrous oxide) gas, and Ar (7 rugon) gas is introduced from the gas supply system 20, and the pressure in the reaction chamber 11 is increased to k1O-3To.
It was set to rr. Next, the magnetic field formed by the magnet 16 is set to 800 Gauss near the sample 19, the power density applied by the power supply mechanism 12 is set to IW,/(-nl, and the bias applied to the sample K is set to 800 Gauss). The voltage k was set at 100 V, and a silicon oxide film was grown on the aluminum wiring 102 formed on the silicon oxide group 103 formed by thermal chemical vapor deposition as shown in the gi-b diagram.

According to the present invention, in spite of the low bias voltage of 100 V because high-density plasma is completely formed under a pressure of 1 O-3 Torr, as shown in FIG.
02, a flat silicon oxide film 101 can be formed.

Next, using this equipment, a silicon oxide film was formed on a gate length of 1 μm+N channel MOS transistor under the above-mentioned growth conditions, and the threshold voltage of this transistor before and after film formation was investigated. The results are shown in Figure 1-a. show.

It can be seen from this that there is no change in the threshold voltage due to the formation of the film, and that there is no damage to the underlying layer.

Next, Figure 2-a is a longitudinal sectional view of a second embodiment of the present invention. In the reaction chamber 21 equipped with a gas supply system 29 and a vacuum exhaust system 24, a sample stage 26 on which a sample 28 is placed, a counter electrode 27, and a magnetic field application mechanism 25 are provided. Power supply mechanism 2 consisting of a high frequency power source and an impedance matching circuit
By supplying power to the sample 28 through the capacitor 23, an electric field perpendicular to the sample 28 is formed as in the first embodiment. A magnetic field intersecting this electric field is applied by a magnetic field applying mechanism 25. As shown in Figure 2-b, this magnetic field application mechanism 25 rotates around a central axis perpendicular to all the scroll magnets in which the N and S poles are arranged in a spiral. Tani's Applied Physics Association Lecture Proceedings P.

As shown in ``Study of Plasma Application Technology Using Rotating Magnetic Fields'' described in 31, when a scroll magnet is rotated around its entire central axis, it spreads over a wide area near the magnet surface.
It is characterized by the ability to obtain a uniform and strong magnetic field.

A method of forming a silicon oxide film using the apparatus of the second embodiment will be described below. Gas supply 29 to 5iHn gas, N
A mixed gas of No. 20 gas and Ar gas is introduced, and the pressure in the reaction chamber 21 is set to f 10-'' Torr.

Next, the magnetic field application mechanism 25 that applies the entire rotating magnetic field is set so that a magnetic field of 800 Gauss is applied near the sample 28, and the power density 'e I W/f applied by the power supply mechanism 22 is
The bias voltage f, 1o applied to the sample is set to fl.
ov to grow a silicon oxide film. As a result, high-density plasma is generated near the surface of the sample 28, forming a silicon oxide film on the sample 28 that is as dense and flat as the film obtained in the first embodiment. .

In this second embodiment, since a magnetic field applying mechanism 25 for applying a rotating magnetic field is used, a uniform magnetic field is applied over a wide area near the surface of the sample 28, so that the thickness distribution of the silicon oxide film formed is This has the advantage that the film thickness distribution is improved over that of the silicon oxide film formed by the plasma chemical vapor deposition apparatus of the first embodiment.

〔Effect of the invention〕

As explained above, in the plasma chemical vapor deposition apparatus of the present invention, an electric field is applied perpendicularly to the sample, and a magnetic field is applied to cross this electric field. A high-density plasma that is 102 to 103 times higher than the plasma density can be obtained. Since a thin film is formed using this high-density plasma, there is an effect that a film with excellent density and flatness can be formed at a high deposition rate with a low bias voltage. Furthermore, since the film can be formed at a lower bias voltage, there is no damage to sample 1F, and sputter etching of the electrode is suppressed, resulting in a high-quality film free from impurities incorporated into the formed film.

[Brief explanation of the drawing]

FIG. 1-a is a longitudinal sectional view of a first embodiment of the present invention. 1-b is a cross-sectional view when a silicon oxide film is formed on Al wiring using the plasma chemical vapor deposition apparatus according to the first embodiment of the present invention. Figure 1-a shows the threshold voltage values before and after film formation when a silicon oxide film is entirely formed on an N-channel MOS transistor using a plasma chemical vapor deposition apparatus according to the first embodiment of the present invention. It is a diagram. FIG. 2-a is a longitudinal sectional view of a second embodiment of the present invention. FIG. 2-b is a plan view of a scroll magnet used in the magnetic field application mechanism for applying a rotating magnetic field used in the second embodiment. 3-a is a vertical sectional view of a conventionally used plasma chemical vapor deposition apparatus. 3-b is a cross-sectional view when a silicon oxide film is formed on fiAl wiring using a conventional plasma chemical vapor deposition apparatus. 11... Reaction chamber, 12... Power supply mechanism for applying bias voltage, 13... Capacitor, 14... Vacuum exhaust system, 15. −・
...Sample stage, 16...Magnetic field application mechanism, 17.
...Counter electrode, 18...Magnetic field, 19...
...Sample, 20...Reaction gas supply system, 10
1...Silicon oxide N film formed by the plasma chemical vapor deposition apparatus of the present invention, 102...Aluminum wiring, 103...---Thermal chemical vapor deposition method well-formed silicon oxide film, 21... reaction chamber, 22... power supply mechanism for applying bias voltage, 23... capacitor, 24...
... Vacuum exhaust system, 25 ... Magnetic field application mechanism,
26... Sample stage, 27... Counter electrode,
28... Sample, 29... Reaction gas supply system, 201-... N pole of magnet, 202...
・S pole of magnet, 203...(N pole of magnet, 31
...Reaction chamber, 32 ... Vacuum exhaust system, 33
......Power supply mechanism, 34...Capacitor--135...RL 3 G...
・Sample stage, 37...Counter electrode, 38...
・Father gas supply system, 301...Silicon oxide film formed by a conventional plasma chemical vapor deposition apparatus, 3
02... Aluminum wiring, 303...
・Silicon oxide film formed by thermal chemical vapor deposition. Daigo, Bendanshi Uchihara Oto ll two mutual wo Den No. 11 Figure 27: Hf@Hadaoshi 28: Ho Ekifun No. 2 Figure 2 Oral procedure amendment written format) % formula % 1. Indication of the incident Showa 1961 Patent Application No. 178
No. 216 No. 2, Name of the invention Gutsuma chemical vapor deposition cap 3, Relationship to the amended person case Applicant: 5-33-1 Shiba, Minato-ku, Tokyo (423) NEC Corporation Representative: Tadahiro Sekimoto 4 , Agent: Sumitomo Sanda Building, 37-8 Shiba 5-chome, Minato-ku, Tokyo 108 Japan. NEC Corporation (6591) Patent Attorney Uchihara Kai 5 - Telephone Tokyo (03) 456-3111 (main representative) 6, Subject of amendment #! Contents of the amendment to "Brief Description of Drawings" in Part A 1) "Diagram 1-b" on page 10, line 17 of the specification is corrected to "Diagram 1-b." 2) On page 10, line 17 of the specification, "3-a" is corrected to "Figure 3-a." 3) It says "3-b" on page 11, line 11 of the specification.
, corrected as "Figure 3-b". Agent Patent Attorney Uchihara F+.

Claims (1)

[Scope of Claims] 1) In a plasma chemical vapor deposition apparatus that decomposes a material gas by plasma discharge and deposits a thin film on a sample, an electric field forming mechanism that forms an electric field perpendicular to the sample;
A plasma chemical vapor deposition apparatus comprising: a mechanism for applying a magnetic field that crosses the electric field. 2) The electric field forming mechanism includes a first electrode on which the sample is placed and a second electrode facing the first electrode. Plasma chemical vapor deposition equipment. 3) The plasma chemical vapor deposition apparatus according to claim 2, wherein a bias voltage is applied to the first electrode, and a reference potential is applied to the second electrode. 4) The plasma enhanced chemical vapor deposition apparatus according to claim 2, wherein the magnetic field is a magnetic field perpendicular to the electric field formed between the first and second electrodes. 5) The plasma enhanced chemical vapor deposition apparatus according to claim 2, wherein the magnetic field is a magnetic field parallel to the first electrode. 6) The plasma chemical vapor deposition apparatus according to claim 2, wherein the magnetic field is a magnetic field rotating around the central axis of the first electrode.